Grain oriented electrical steel sheet and method for manufacturing the same

Abstract

A method of manufacturing a grain oriented electrical steel sheet includes a rolling a slab for a grain oriented electrical steel sheet to obtain a steel sheet having final sheet thickness; subjecting the steel sheet to decarburizing annealing; coating a surface of the steel sheet with annealing separator mainly composed of MgO; subjecting the steel sheet thus coated to final annealing; providing a tension coating to the steel sheet; and subjecting the steel sheet to magnetic domain refinement by laser irradiation after either the final annealing or provision of the tension coating, wherein (1) the coating weight of the anneal separator is at least 10.0 g/m 2 ; (2) coiling tension at which the steel sheet is coiled after being coated with the annealing separator is 30 N/mm 2 to 150 N/mm 2 ; and (3) the average cooling rate in cooling process of the final annealing down to 700° C. is 50° C./hour or less.

1 . A method of manufacturing a grain oriented electrical steel sheet comprising:
 rolling a slab for a grain oriented electrical steel sheet to obtain a steel sheet having final sheet thickness;   subjecting the steel sheet to decarburizing annealing;   coating a surface of the steel sheet with annealing separator mainly composed of MgO;   subjecting the steel sheet thus coated to final annealing;   providing a tension coating to the steel sheet; and   subjecting the steel sheet to magnetic domain refinement by laser irradiation after either the final annealing or provision of the tension coating, wherein   (1) the coating weight of the anneal separator is at least 10.0 g/m 2 ;   (2) coiling tension at which the steel sheet is coiled after being coated with the annealing separator is 30 N/mm 2  to 150 N/mm 2 ; and   (3) the average cooling rate in cooling process of the final annealing down to 700° C. is 50° C./hour or less.   
     
     
         2 . The method of  claim 1 , further comprising subjecting the slab to the hot rolling, optionally, hot-band annealing, and either one cold rolling operation or at least two cold rolling operations with intermediate annealing therebetween to obtain a steel sheet having the final sheet thickness. 
     
     
         3 . A method of manufacturing a grain oriented electrical steel sheet comprising:
 rolling a slab for a grain oriented electrical steel sheet to obtain a steel sheet having final sheet thickness;   subjecting the steel sheet to decarburizing annealing;   coating a surface of the steel sheet with annealing separator mainly composed of MgO;   subjecting the steel sheet thus coated to final annealing;   providing a tension coating to the steel sheet; and   subjecting the steel sheet to magnetic domain refinement by electron beam irradiation after either the final annealing or provision of the tension coating, wherein   (1) the coating weight of the anneal separator is at least 10.0 g/m 2 ;   (2) coiling tension at which the steel sheet is coiled after being coated with the annealing separator is 30 N/mm 2  to 150 N/mm 2 ; and   (3) the average cooling rate in cooling process of the final annealing down to 700° C. is 50° C./hour or less.   
     
     
         4 . The method of  claim 3 , further comprising subjecting the slab to the hot rolling, optionally, hot-band annealing, and either one cold rolling operation or at least two cold rolling operations with intermediate annealing therebetween to obtain a steel sheet having the final sheet thickness.